CN103631698A - Camera PTZ (pan/tilt/zoom) control method and device for target tracking - Google Patents

Abstract

The invention belongs to the field of video monitoring, and provides a camera PTZ (pan/tilt/zoom) control method and device for target tracking. The method comprises the steps of obtaining the relative position of a tracked target in a video frame; setting the camera grade speed in each region, wherein the setting of the grade speed is determined according to the relative position of the tracked target deviating from the center point of the frame image in the video frame, and the farther the relative position is from the center point, the higher the camera grade speed goes; converting the camera grade speed into a camera reference angular speed; calculating the current camera actual angular speed according to the camera reference angular speed; converting the current camera actual angular speed into a camera actual output grade speed. The method and device provided by the invention can achieve an aim of accurately controlling the camera to rotate at different grade speeds in different areas so as to realize an effect of accurate positioning and smooth transition of the camera, and the phenomena of stuck, discontinuous and unsmooth movement of the existing camera are solved.

Description

A kind of video camera PTZ control methods and device for target following

Technical field

The present invention relates to field of video monitoring, more particularly to one kind is in PTZ（Pan/Tilt/Zoom writes a Chinese character in simplified form, and represents head comprehensive（Up and down, left and right）Mobile and camera lens zoom, Zoom control）The method and device being controlled during target following to video camera.

Background technology

In field of video monitoring, Pan/Tilt/Zoom camera is widely used in the target following of broad regions.Compared to the video camera of traditional fixing camera, PTZ has the multiple advantages such as wide monitoring range, the increase of tracking target scene and variable focal length, utilize these advantages, with reference to video image analysis, target following positioning and the control of Pan/Tilt/Zoom camera, tracked target can be tracked in certain scene, captured and alarm linkage.

Current PTZ tracking techniques lay particular emphasis on the optimization and improvement of algorithm aspect mostly, But most of algorithms is to realize the prediction of target location according to the multilevel iudge of present frame and front and rear several frames, when receiving various interference, such as illumination, deformation, block, picture quality and color of object change, algorithm will be difficult to the accurate location of offer tracked target, so that the problems such as causing tracking target loss and inaccurate predicted position.The track algorithm that so places one's entire reliance upon carries out the control of Pan/Tilt/Zoom camera, will cause larger error.

And, current most of PTZ tracking techniques be it is single calculate target location by algorithm and be available to video camera make with reference to determine moving direction, and actual conditions are when the object moves, if do not take any strategy in whole picture only can cause various problems by single video camera move, if such as camera motion speed is excessively slow, it can cause to track the area of visual field that target disappears in PTZ video pictures, lose tracking target.Picture weave phenomenon can be produced if the overall motion amplitude of video camera or moving step sizes are excessive, while influenceing track algorithm in turn again, causes track algorithm unstable.In the case of producing cumulative errors during algorithm prediction simultaneously, the positional information for continuing to calculate according to algorithm can also produce serious tracking mistake and tracking target loss situation to manipulate video camera.And also easily there is video camera interim card or video camera drift, beyond drawbacks such as the visuals field of tracked target in the existing method that camera motion is only directly controlled by video camera move.

The content of the invention

In view of this, the present invention proposes a kind of video camera PTZ control methods and device for target following, it can reach that precise control video camera is rotated according to different zones with the step velocitys such as different, make video camera reach be accurately positioned, the effect of smooth transition, solve interim card and discontinuous, unsmooth phenomenon that existing video camera occurs when mobile.

The present invention provides a kind of video camera PTZ control methods for target following, comprises the following steps：

Obtain the relative position of tracked target in the video frame；

Subregion sets camera grade speed；

The relative position that setting etc. step velocity deviates the two field picture central point according to tracked target in the video frame determines that relative position distance center point is more remote, and camera grade speed is bigger；

It is video camera reference angular speed by camera grade rate conversion；

Current camera actual angular speed is calculated with reference to turn meter according to the video camera；

Current camera actual angular speed is converted into the step velocitys such as video camera reality output.

Wherein, subregion setting camera grade speed, formula is as follows：

The step velocitys such as X-direction

Wherein X_MOVERepresent the step velocitys such as video camera minimum movement, for constant, variable a, b, c......z are the corresponding video camera empirical value in each region, and posx is the x coordinate of tracked target position point, width represents picture traverse, and abs refers to take absolute value to the content in bracket；

The step velocitys such as Y direction

Wherein Y_MOVEThe step velocitys such as video camera minimum movement are represented, are constant, variables A, B, C.....Z are the corresponding video camera empirical value in each region, and posy is the y-axis coordinate of tracked target position point, and height represents picture altitude.

Wherein, when being divided into 3 regions, video camera empirical value a=50, b=30 in the X-direction grade speed formula；Video camera empirical value A=40, B=30 in Y direction grade speed formula.

Wherein, described is video camera reference angular speed by camera grade rate conversion, and formula is as follows：

Horizontal direction：

V_x=θ_pan=p1Pan₀ ²+p2Pan₀+p3

Wherein, the coefficient that p1, p2, p3 draw for actual test, the coefficient that different cameras is tested and calculated is different；

Vertical direction：

V_y=θ_tilt=t1Tilt₀ ²+t2Tilt₀+t3

The coefficient that wherein t1, t2, t3 draw for actual test, the coefficient that different cameras is tested and calculated is different.

Wherein, described to calculate current camera actual angular speed with reference to turn meter according to video camera, formula is as follows：

Horizontal direction：

$V_{x\_\mathrm{new}}=2*\arctan (\tan \left(\frac{V_x}{2}\right)*\frac{d_0}{d_1})$

Vertical direction：

$V_{y\_\mathrm{new}}=2*\arctan (\tan \left(\frac{V_y}{2}\right)*\frac{d_0}{d_1})$

Wherein d₀For initialization object distance, scope is 5-8 meters, d₁For current object distance.

Wherein, the d₀Initialization object distance is set to 6 meters.

Wherein, described that current camera actual angular speed is converted into the step velocitys such as video camera reality output, formula is as follows：

Solve horizontal direction video camera actual angular speed：

V_{x_new}=θ_pan=p1Pan₀ ²+p2Pan₀+p3

Obtain the step velocitys such as horizontal direction video camera reality output：

${\mathrm{Pan}}_{\mathrm{new}}=\frac{-p2+\sqrt{{p2}^2-4p1(p3-V_{x\_\mathrm{new}})}}{2p1}$

Solve vertical direction video camera actual angular speed：

V_{y_new}=θ_pan=t1Tilt₀ ²+t2Tilt₀+t3

Obtain the step velocitys such as vertical direction video camera reality output：

${\mathrm{Tilt}}_{\mathrm{new}}=\frac{-t2+\sqrt{{t2}^2-4t1(t3-V_{y\_\mathrm{new}})}}{2t1}$

Wherein, the division between the subregion setting camera grade speed, region can be that equidistant partition or Unequal distance are divided.

Wherein, the region of the division is three regions, and the movement velocity that range image central point respectively is video camera between first area, second area, the 3rd region, each region from the near to the remote is different；The step velocity such as what video camera was moved in first area be less than second area move etc. step velocity, video camera second area move etc. step velocity less than the 3rd regional movement etc. step velocity.

The present invention also provides a kind of video camera PTZ control devices for target following, including：

Target location acquisition module, for obtaining the relative position of tracked target in the video frame；

Etc. step velocity setting module, camera grade speed is set for subregion, the distance that the setting etc. step velocity deviates the two field picture central point according to tracked target in the video frame determines that distance center point is more remote, and camera grade speed is bigger；

Reference angle rate conversion module, for being video camera reference angular speed by camera grade rate conversion；

Actual angular speed computing module, for calculating current camera actual angular speed with reference to turn meter according to video camera；

Actual grade rate conversion module, for current camera actual angular speed to be converted into the step velocitys such as video camera reality output.

The method of the invention and device are by detecting tracked target relative position apart from image center in video frame images, and according to relative position information calculate video camera different zones etc. step velocity, it is video camera reference angular speed by grade rate conversion, and current camera actual angular speed is calculated with reference to turn meter according to video camera, current camera actual angular speed is converted into the step velocitys such as video camera reality output again, so as to reach purpose that precise control video camera is rotated according to different zones with the step velocitys such as different, video camera is reached to be accurately positioned, the effect of smooth transition, solve interim card that existing video camera occurs when mobile and discontinuous, unsmooth phenomenon.

Brief description of the drawings

In order to illustrate more clearly about the embodiment of the present invention or technical scheme of the prior art, the accompanying drawing to be used needed for embodiment or description of the prior art will be briefly described below, apparently, drawings in the following description are only some embodiments of the present invention, for those of ordinary skill in the art, on the premise of not paying creative work, other accompanying drawings can also be obtained according to these accompanying drawings.

Fig. 1 is a kind of video camera PTZ control method flow charts for target following of the embodiment of the present invention one；

Fig. 2 is a kind of video camera PTZ control method flow charts for target following of the embodiment of the present invention two；

Fig. 3 is the region division schematic diagram of the embodiment of the present invention two；

Fig. 4 is the horizontal direction conic fitting schematic diagram of the embodiment of the present invention two；

Fig. 5 is the vertical direction conic fitting schematic diagram of implementation two of the invention；

Fig. 6 is a kind of video camera PTZ control device schematic diagrames for target following of the embodiment of the present invention three.

Embodiment

Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is clearly and completely described, it is clear that described embodiment is only a part of embodiment of the invention, rather than whole embodiments.Based on the embodiment in the present invention, the every other embodiment that those of ordinary skill in the art are obtained under the premise of creative work is not made belongs to the scope of protection of the invention.

Embodiment one：

Referring to Fig. 1, it is a kind of flow chart of video camera PTZ control methods for target following provided in an embodiment of the present invention, following steps are specifically included：

S101, the relative position of acquisition tracked target in the video frame.

In the present embodiment, relative position refers to tracked target in the video frame apart from the relative position of the two field picture central point；

X-axis horizontal direction relative position can pass through formula

Calculate；

Wherein, posx is the x coordinate of tracked target position point, and widt represents picture traverse, and abs refers to take absolute value to the content in bracket；

Y-axis vertical direction relative position can pass through formula

Calculate；

Wherein, posy is the y-axis coordinate of tracked target position point, and teight represents picture altitude.

S102, subregion setting camera grade speed.

The relative position that setting etc. step velocity deviates the two field picture central point according to tracked target in the video frame determines that relative position distance center point is more remote, and camera grade speed is bigger.

The present invention can set 0-N region in video frame images（N is positive integer）, specific region division number according to circumstances depending on, the division between region can be that equidistant partition or Unequal distance are divided.The camera grade speed set by region that the equidistant or Unequal distance is divided is calculated using equation below：

The step velocitys such as X-direction

Wherein X_MOVEThe step velocitys such as video camera minimum movement are represented, are constant, variable a, b, c......z are different zones（It is divided into N number of region）Corresponding video camera empirical value, posx is the x coordinate of tracked target position point, and width represents picture traverse, and abs refers to take absolute value to the content in bracket；

It is tracked target in the video frame apart from the horizontal relative position of X-axis of the two field picture central point；

The step velocitys such as Y direction

Wherein Y_MOVEThe step velocitys such as video camera minimum movement are represented, are constant, variables A, B, C......Z are different zones（It is divided into N number of region）Corresponding video camera empirical value, posy is the y-axis coordinate of tracked target position point, and height represents picture altitude；

It is tracked target in the video frame apart from the Y-axis vertical direction relative position of the two field picture central point.

S103, by camera grade rate conversion it is video camera with reference to angular speed.

Specifically, formula is as follows：

Horizontal direction：

V_x=θ_pan=p1Pan₀ ²+p2Pan₀+p3

Wherein, the coefficient that p1, p2, p3 draw for actual test, the coefficient that different cameras is tested and calculated is different；

Vertical direction：

V_y=θ_tilt=t1Tilt₀ ²+t2Tilt₀+t3

Wherein, the coefficient that t1, t2, t3 draw for actual test, the coefficient that different cameras is tested and calculated is different.

S104, current camera actual angular speed calculated with reference to turn meter according to video camera.

Specifically, formula is as follows：

Horizontal direction：

$V_{x\_\mathrm{new}}=2*\arctan (\tan \left(\frac{V_x}{2}\right)*\frac{d_0}{d_1})$

Vertical direction：

$V_{y\_\mathrm{new}}=2*\arctan (\tan \left(\frac{V_y}{2}\right)*\frac{d_0}{d_1})$

Wherein d₀For initialization object distance, scope is 5-8 meters, d₁Current object distance.

S105, current camera actual angular speed is converted into the step velocitys such as video camera reality output.

Specifically, formula is as follows；

Solve horizontal direction video camera actual angular speed：

V_{x_new}=θ_pan=p1Pan₀ ²+p2Pan₀+p3

Obtain the step velocitys such as horizontal direction video camera reality output：

${\mathrm{Pan}}_{\mathrm{new}}=\frac{-p2+\sqrt{{p2}^2-4p1(p3-V_{x\_\mathrm{new}})}}{2p1}$

Solve vertical direction video camera actual angular speed：

V_{y_new}=θ_pan=t1Tilt₀ ²+t2Tilt₀+t3

Obtain the step velocitys such as vertical direction video camera reality output：

${\mathrm{Tilt}}_{\mathrm{new}}=\frac{-t2+\sqrt{{t2}^2-4t1(t3-V_{y\_\mathrm{new}})}}{2t1}$

Provided by the present invention for target following video camera PTZ control methods by detecting tracked target relative position apart from image center in video frame images, and according to relative position information calculate video camera different zones etc. step velocity, it is video camera reference angular speed by grade rate conversion, and current camera actual angular speed is calculated with reference to turn meter according to video camera, current camera actual angular speed is converted into the step velocitys such as video camera reality output again, so as to reach purpose that precise control video camera is rotated according to different zones with the step velocitys such as different, video camera is reached to be accurately positioned, the effect of smooth transition, solve the existing interim card occurred in mobile camera and discontinuous, unsmooth phenomenon.

Embodiment two：

Referring to Fig. 2, describing concrete methods of realizing of the present invention in detail exemplified by the region of three ranks is set in video frame images below.

S201, in range image central point divide first area successively from the near to the remote（Hereinafter referred to as 1st area）, second area（Hereinafter referred to as 2nd area）, the 3rd region（Hereinafter referred to as 3rd area）As shown in figure 3, in the region of each rank, camera motion etc. step velocity it is different.Intuitively, the step velocity such as what video camera was moved in first area be less than second area move etc. step velocity, video camera second area move etc. step velocity be less than the 3rd regional movement etc. step velocity, that is movement velocity of the video camera in 3rd area is fast, and movement velocity of the video camera in 2nd area is slow with respect to 3rd area, 1st area is camera motion stop area.Thus, realizing tracked target in the different strategy of different zones camera motion speed.

For convenience of description, we provide that 3 → 2 expression video cameras are moved from 3rd area to 2nd area；2 → 1 expression video cameras are moved from 2nd area to 1st area.In the present embodiment, the length for choosing 2 region picture frames is 30 pixels, and the length of 3 region picture frames is 40 pixels, the point centered on video frame images center.

Specifically, when tracked target passes through different zones, the motion state of video camera is also different, described in detail below：

When tracked target is by 1 → 2 motion process, i.e., tracked target is at 1,2nd area, video camera stop motion.

When tracked target is by 3 → 2 motion processes, camera motion speed is determined that distance center point is more remote, and camera grade speed is bigger by the off-center point distance of tracked target.

S202, calculating camera grade speed,

Formula is as follows：

The step velocitys such as X-direction

Wherein X_MOVEThe step velocitys such as video camera minimum movement are represented, are constant, variable a, b are video camera empirical value, and posx is the x coordinate of tracked target position point, and width represents picture traverse, and abs refers to take absolute value to the content in bracket；

It is tracked target in the video frame apart from the horizontal relative position of X-axis of the two field picture central point.

In the present embodiment, video camera the empirical value a=50, b=30.

The step velocitys such as Y direction

Wherein Y_MOVEThe step velocitys such as video camera minimum movement are represented, are constant, variables A, B are video camera empirical value, and posy is the y-axis coordinate of tracked target position point, and height represents picture altitude；

It is tracked target in the video frame apart from the horizontal relative position of Y-axis of the two field picture central point.

In the present embodiment, video camera empirical value A=40, B=30.

S203, by camera grade rate conversion it is video camera with reference to angular speed.

The relation that can draw the position relationship of camera grade speed and video camera in quadratic polynomial is fitted by test data of experiment.

Horizontal direction reference angle velocity fitting relational result is as follows：

V_x=θ_pan=p1Pan₀ ²+p2Pan₀+p3

Wherein, the coefficient that p1, p2, p3 draw for actual test

Specific experiment step is as follows：

1st, by testing the method for sampling, the numerical value pair for the angular speed that the step velocity such as acquisition camera and video camera are rotated.Specifically numerical value is to as shown in the table：

2nd, carried out by MATLAB after conic fitting as shown in figure 4, horizontal direction quadratic polynomial coefficient can be obtained by carrying out curve parametric solution.

The measured coefficient of this experiment is p1=0.0146882198460146；P2=0.177564108309657；P3=0.384162267296462, the coefficient is only for reference, and the system that different cameras is calculated is different.

Vertical direction reference angle velocity fitting relational result is as follows：

V_y=θ_tilt=t1Tilt₀ ²+t2Tilt₀+t3

Wherein, the coefficient that t1, t2, t3 draw for actual test.

Specific experiment step is as follows：

1st, by testing the method for sampling, the numerical value pair for the angular speed that the step velocity such as acquisition camera and video camera are rotated.Numerical value is to as shown in the table：

2nd, carried out by MATLAB after conic fitting as shown in figure 5, vertical direction quadratic polynomial coefficient can be obtained by carrying out curve parametric solution.

The measured coefficient of this experiment is t1=0.0157007973259717；

t2=0.131463431400743；T3=0.848592317219867, only for reference, the coefficient that different cameras is calculated is different.

S204, current camera actual angular speed calculated with reference to turn meter according to video camera.

Specifically, formula is as follows：

Horizontal direction：

$V_{x\_\mathrm{new}}=2*\arctan (\tan \left(\frac{V_x}{2}\right)*\frac{d_0}{d_1})$

Vertical direction：

$V_{y\_\mathrm{new}}=2*\arctan (\tan \left(\frac{V_y}{2}\right)*\frac{d_0}{d_1})$

Wherein d₀For initialization object distance, scope is 5-8 meters, d₁Current object distance.

In the present embodiment, the d₀It it is 6 meters for initialization object distance.

S205, current camera actual angular speed is converted into the step velocitys such as video camera reality output.

Specifically, formula is as follows；

Solve horizontal direction video camera actual angular speed：

V_{x_new}=θ_pan=p1Pan₀ ²+p2Pan₀+p3

Obtain the step velocitys such as horizontal direction video camera reality output：

${\mathrm{Pan}}_{\mathrm{new}}=\frac{-p2+\sqrt{{p2}^2-4p1(p3-V_{x\_\mathrm{new}})}}{2p1}$

Finally give Pan_newFor camera horizon direction reality output etc. step velocity.

Solve vertical direction video camera actual angular speed：

V_{y_new}=θ_pan=t1Tilt₀ ²+t2Tilt₀+t3

Obtain the step velocitys such as vertical direction video camera reality output：

${\mathrm{Tilt}}_{\mathrm{new}}=\frac{-t2+\sqrt{{t2}^2-4t1(t3-V_{y\_\mathrm{new}})}}{2t1}$

Finally give Tilt_newFor video camera vertical direction reality output etc. step velocity.

S206, by the level obtained in S205, vertical direction reality output etc. step velocity export and give video camera the corresponding interface, pass through pelco-d agreements and serial port protocol control video camera to rotate.

The embodiment of the present invention is by detecting tracked target relative position apart from image center in video frame images, and according to relative position information calculate video camera different zones etc. step velocity, and be video camera reference angular speed by grade rate conversion, and the actual angular speed of current camera is calculated with reference to turn meter according to video camera, current camera actual angular speed is converted into the step velocitys such as video camera reality output again, so as to reach purpose that precise control video camera is rotated according to different zones with the step velocitys such as different, video camera is reached to be accurately positioned, the effect of smooth transition, solve the existing interim card occurred in mobile camera and discontinuous, unsmooth phenomenon.

The method of the invention achieves the progress on Pan/Tilt/Zoom camera Precise control direction, the effect that PTZ controls and control by stages camera grade speed are carried out independent of algorithm is reached, the degree of accuracy of tracking target is improved, is that the more stable calculating of algorithm provides the foundation.The method of the invention solve it is existing only by video camera move come direct mobile camera easily occur video camera interim card or video camera drift about, beyond the visual field of tracked target the drawbacks of.

Embodiment three：

The present invention also provides a kind of video camera PTZ control devices for target following, refer to Fig. 6, its be a kind of video camera PTZ control device schematic diagrames for target following provided in an embodiment of the present invention, specifically include target location acquisition module 601, etc. step velocity setting module 602, angular speed modular converter 603, actual angular speed modular converter 604, actual grade rate conversion module 605, etc. step velocity output module 606；Each module concrete function is as follows：

Target location acquisition module 601, for obtaining the relative position of tracked target in the video frame.

Specifically, the target for needing to track can be selected by two ways, one kind is to manually select tracked target；Another is that regular score line is carried out in designated area, is such as hovered, the formulation of reverse and warning region, and correspondence target following detection is carried out after respective rule is triggered.Determine that tracking position of object refers to export target location after object detection method or method for tracking target processing.Target following detection is carried out by many algorithms fusion in the present invention, target following is carried out including optical flow tracking algorithm, average drifting track algorithm, dynamic background frames difference algorithm etc..

Etc. step velocity setting module 602, camera grade speed is set for subregion, the relative position that setting etc. step velocity deviates the two field picture central point according to tracked target in the video frame determines that relative position distance center point is more remote, and camera grade speed is bigger.

The present invention can actually set 0-N region in video frame images（N is positive integer）, specific region division number according to circumstances depending on, the division between region can be that equidistant partition or Unequal distance are divided.

Formula etc. step velocitys such as the settings of step velocity setting module 602 is as follows：

The step velocitys such as X-direction

Wherein X_MOVEThe step velocitys such as video camera minimum movement are represented, are constant, variable a, b......z are different zones（It is divided into N number of region）Corresponding video camera empirical value, posx is the x coordinate of tracked target position point, and width represents picture traverse, and abs refers to take absolute value to the content in bracket；

It is tracked target in the video frame apart from the horizontal relative position of X-axis of the two field picture central point；

The step velocitys such as Y direction

Wherein Y_MOVEThe step velocitys such as video camera minimum movement are represented, are constant, variables A, B......Z are different zones（It is divided into N number of region）Corresponding video camera empirical value, posy is the y-axis coordinate of tracked target position point, and height represents picture altitude；

It is tracked target in the video frame apart from the horizontal relative position of Y-axis of the two field picture central point.

Reference angle rate conversion module 603, for being video camera reference angular speed by camera grade rate conversion.

Specifically, the computing formula of angular speed modular converter 603 is as follows：

Horizontal direction：

V_x=θ_pan=p1Pan₀ ²+p2Pan₀+p3

Wherein, the coefficient that p1, p2, p3 draw for actual test, the coefficient that different cameras is tested and calculated is different；

Vertical direction：

V_y=θ_tilt=t1Tilt₀ ²+t2Tilt₀+t3

Wherein, the coefficient that t1, t2, t3 draw for actual test, the coefficient that different cameras is tested and calculated is different.

Actual angular speed computing module 604, for calculating current camera actual angular speed with reference to turn meter according to video camera.

Specifically, the computing formula of actual angular speed computing module 604 is as follows：

Horizontal direction：

$V_{x\_\mathrm{new}}=2*\arctan (\tan \left(\frac{V_x}{2}\right)*\frac{d_0}{d_1})$

Vertical direction：

$V_{y\_\mathrm{new}}=2*\arctan (\tan \left(\frac{V_y}{2}\right)*\frac{d_0}{d_1})$

Wherein d₀For initialization object distance, scope is 5-8 meters, d₁Current object distance.

In one embodiment, the d₀It is 6 meters to initialize object distance.

Actual grade rate conversion module 605, for current camera actual angular speed to be converted into the step velocitys such as video camera reality output.

Specifically, the conversion formula that current camera actual angular speed is converted to the step velocitys such as video camera reality output by actual grade rate conversion module 605 is as follows；

Solve horizontal direction video camera actual angular speed：

V_{x_new}=θ_pan=p1Pan₀ ²+p2Pan₀+p3

Obtain the step velocitys such as horizontal direction video camera reality output：

${\mathrm{Pan}}_{\mathrm{new}}=\frac{-p2+\sqrt{{p2}^2-4p1(p3-V_{x\_\mathrm{new}})}}{2p1}$

Finally give Pan_newFor camera horizon direction reality output etc. step velocity.

Solve vertical direction video camera actual angular speed：

V_{y_new}=θ_pan=t1Tilt₀ ²+t2Tilt₀+t3

Obtain the step velocitys such as vertical direction video camera reality output：

${\mathrm{Tilt}}_{\mathrm{new}}=\frac{-t2+\sqrt{{t2}^2-4t1(t3-V_{y\_\mathrm{new}})}}{2t1}$

Finally give Tilt_newFor video camera vertical direction reality output etc. step velocity.

Etc. step velocity output module 606, the level that actual grade rate conversion module 605 is obtained, vertical direction reality output etc. step velocity send video camera the corresponding interface to, pass through pelco-d agreements and serial port protocol and control video camera to rotate.

The purpose that precise control video camera is rotated according to tracked target slip chart as the distance of centerline with the step velocitys such as different can be reached using device of the present invention, make video camera reach be accurately positioned, the effect of smooth transition, solve the existing interim card occurred in mobile camera and discontinuous, unsmooth phenomenon.

One of ordinary skill in the art will appreciate that realizing all or part of flow in above-described embodiment method, computer program is can be by instruct the hardware of correlation to complete, described program can be stored in a computer read/write memory medium, the program is upon execution, it may include such as the flow of the embodiment of above-mentioned each method.Wherein, described storage medium can be magnetic disc, CD, read-only memory（Read-Only Memory, ROM）Or random access memory（Random Access Memory, RAM）Deng.

Above disclosure is only preferred embodiment of present invention, can not limit the interest field of the present invention, therefore the equivalent variations made according to the claims in the present invention with this certainly, still belongs to the scope that the present invention is covered.

Claims (10)

1. a kind of video camera PTZ control methods for target following, it is characterised in that comprise the following steps： 

Obtain the relative position of tracked target in the video frame； 

Subregion sets camera grade speed； 

The relative position that setting etc. step velocity deviates the two field picture central point according to tracked target in the video frame determines that relative position distance center point is more remote, and camera grade speed is bigger； 

It is video camera reference angular speed by camera grade rate conversion； 

Current camera actual angular speed is calculated with reference to turn meter according to the video camera； 

Current camera actual angular speed is converted into the step velocitys such as video camera reality output. 

2. the video camera PTZ control methods according to claim 1 for target following, it is characterised in that subregion sets camera grade speed, formula is as follows： 

The step velocitys such as X-direction

Wherein X_MOVERepresent the step velocitys such as video camera minimum movement, for constant, variable a, b, c......z are the corresponding video camera empirical value in each region, and posx is the x coordinate of tracked target position point, Width represents picture traverse, and abs refers to take absolute value to the content in bracket； 

The step velocitys such as Y direction

Wherein Y_MOVEThe step velocitys such as video camera minimum movement are represented, are constant, variables A, B, C.....Z are the corresponding video camera empirical value in each region, and posy is the y-axis coordinate of tracked target position point, and height represents picture altitude. 

3. the video camera PTZ control methods according to claim 2 for target following, it is characterised in that when being divided into 3 regions, video camera empirical value a=50, b=30 in the X-direction grade speed formula；Video camera empirical value A=40, B=30 in Y direction grade speed formula. 

4. the video camera PTZ control methods for target following according to any one of claims 1 to 3, it is characterised in that described is video camera reference angular speed by camera grade rate conversion, and formula is as follows： 

Horizontal direction： 

V_x=θ_pan=p1Pan₀ ²+p2_Pan₀+p3 

Wherein, the coefficient that p1, pl, p3 draw for actual test, the coefficient that different cameras is tested and calculated is different； 

Vertical direction： 

V_y=θ_tilt=t1Tilt₀ ²+t2Tilt₀+t3 

The coefficient that wherein t1, tl, t3 draw for actual test, the coefficient that different cameras is tested and calculated is different. 

5. the video camera PTZ control methods according to claim 4 for target following, it is characterised in that described to calculate current camera actual angular speed with reference to turn meter according to video camera, formula is as follows： 

Horizontal direction： 

Vertical direction： 

Wherein d₀For initialization object distance, scope is 5-8 meters, d₁For current object distance. 

6. the video camera PTZ control methods according to claim 5 for target following, it is characterised in that the d₀Initialization object distance is set to 6 meters. 

7. the video camera PTZ control methods according to claim 4 for target following, it is characterised in that described that current camera actual angular speed is converted into the step velocitys such as video camera reality output, formula is as follows： 

Solve horizontal direction video camera actual angular speed： 

V_{x_new}=θ_pan=p1Pan₀ ²+p2Pan₀+p3 

Obtain the step velocitys such as horizontal direction video camera reality output： 

Solve vertical direction video camera actual angular speed： 

V_{y_new}=θ_pan=t1Tilt₀ ²+t2Tilt₀+t3 

Obtain the step velocitys such as vertical direction video camera reality output： 

。

8. the video camera PTZ control methods according to claim 7 for target following, it is characterised in that the division that the subregion sets between camera grade speed, region can be that equidistant partition or Unequal distance are divided. 

9. the video camera PTZ control methods according to claim 7 for target following, it is characterized in that, the region of the division is three regions, the movement velocity that range image central point respectively is video camera between first area, second area, the 3rd region, each region from the near to the remote is different；The step velocity such as what video camera was moved in first area be less than second area move etc. step velocity, video camera second area move etc. step velocity less than the 3rd regional movement etc. step velocity. 

10. a kind of video camera PTZ control devices for target following, it is characterised in that including： 

Target location acquisition module, for obtaining the relative position of tracked target in the video frame； 

Etc. step velocity setting module, camera grade speed is set for subregion, the distance that the setting etc. step velocity deviates the two field picture central point according to tracked target in the video frame determines that distance center point is more remote, and camera grade speed is bigger； 

Reference angle rate conversion module, for being video camera reference angular speed by camera grade rate conversion； 

Actual angular speed computing module, for calculating current camera actual angular speed with reference to turn meter according to video camera； 

Actual grade rate conversion module, for current camera actual angular speed to be converted into the step velocitys such as video camera reality output. 

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